如何在MKMap中获得邮政编码。(swift3.0)

import MapKit

let location = CLLocationCoordinate2D(latitude: 37.331686, longitude: -122.030656)
let searchRequest = MKLocalSearch.Request()
searchRequest.naturalLanguageQuery = "Apple Inc."
searchRequest.region = MKCoordinateRegion(center: location, span: MKCoordinateSpan(latitudeDelta: 0.1, longitudeDelta: 0.1))

let localSearch = MKLocalSearch(request: searchRequest)
localSearch.start { (response, error) in
    guard let response = response else {
        if let error = error {
            print("搜索失败：\(error.localizedDescription)")
        }
        return
    }
    
    // 处理搜索结果
    for mapItem in response.mapItems {
        if let postalAddress = mapItem.placemark.postalAddress {
            let postalCode = postalAddress.postalCode
            print("邮政编码：\(postalCode)")
        }
    }
}